Electrophotographic charging apparatus comprising needle point discharge electrodes and concave shield electrodes

ABSTRACT

A corona discharger for electrophotography comprises at least one needle electrode structure and at least one shielding member disposed opposite to the needles of the electrode structure. Main corona discharge is generated between the end of each needle of the electrode structure and the shielding member to impress a charge on a photosensitive sheet. The unique needle electrode structure and shielding member are formed and arranged to apply uniform charge to the photosensitive sheet with high efficiencies.

United States Patent [72] Inventors Aklra Kurahashi;

Masayoshi Ishihara; Giichi Marushima, all of Tokyo, Japan [21] Appl. No, 777,215

[22] Filed Nov. 20, 1968 [45] Patented Nov. 30, 1971 [73] Assignee Cannon Camera Kabushlki Kaisha Ohta-ku, Tokyo, Japan [32] Priorities Nov. 28, 1967 [33] Japan Dec. 18, 1967,Japan, No. 42/81053; Dec. 28, 1967,,Iapan, No. 42/110564; Apr. 1, 1968, Japan, No. 43/21307 [54] ELECTROPl-IOTOGRAPHIC CHARGING APPARATUS COMPRISING NEEDLE POINT DISCHARGE ELECTRODES AND CONCAVE SHIELD ELECTRODES 13 Claims, 16 Drawing Figs.

[52] U.S. Cl 250/495 ZC, 250/4956 GC [51] Int. Cl G03g 15/00 [50] Field of Search 250/49561,

[56] References Cited UNITED STATES PATENTS 3,003,404 10/1961 Metcalfe 250/495 2,965,755 12/1960 West 250/495 3,194,131 7/1965 Robinson .1 250/495 3,237,068 2/1966 Sowiak 250/495 3,307,034 2/1967 Bean i i 250/495 3,382,361 5/1968 Schomburg. 250/495 3,456,109 7/1969 Gawron 250/495 Primary Examiner-James W. Lawrence Assistant ExaminerC. E. Church Arl0rneyWatson Leavenworth & Kelton ABSTRACT: A corona discharger for electrophotography comprises at least one needle electrode structure and at least one shielding member disposed opposite to the needles of the electrode structure. Main corona discharge is generated between the end of each needle of the electrode structure and the shielding member to impress a charge on a photosensitive sheet. The unique needle electrode structure and shielding member are formed and arranged to apply uniform charge to the photosensitive sheet with high efiiciencies.

PATENTEDHUVSOISYI 3,624,392

sum 1 OF 4 FIG. 1 PmoR ART s if 2 93 91 I N VliN'l ()R AKIRA KURASHL, MASAYOSHI ISHIIIARA and BY GIICHI MARUSHIMA MARN 81 JANGARA'IHIS Attornuys for Applicants PATENIED mwso I971 FIG.5

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SHEET 2 0F 4 POWER SUPPLY Y GIICHI MARUSHIMA MARN & JANGARATHIS Attorneys for Applicants PATENTEU NUVBOIS?! 3.624.392

SHEEI3UF4 FIG.8 FIG-9 L @14 P l FIG.IO

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IVVVV' INVIZN'I'UR. AKIRA KURAHASIH, MASAYOSHI ISHIHARA and BY 011cm MARUSHIMA MARN K1 JANCEARA'JHIS Attornvys l'nr Applil-untn PATENIEDnnvaom 3, 24,392

SHEET '4 OF 4 PIC-516 INVI'IN'I'UR. AKIRA KURAHASH], MASAYOSHI ISHIHARA and GIICHI MARUSHIMA MARN K: JANGARATHIS Attorneys for Applu-ants ELECTROPHOTOGRAPI-IIG CHARGING APPARATUS COMPRISING NEEDLE POINT DISCHARGE ELECTRODES AND CONCAVE SHIELD ELECTRODES This invention relates to an improvement of a corona discharger for electrophotography. The discharging electrodes for use in the corona discharger for impressing an electrostatic charge on the photosensitive layer are classified into two kinds of electrodes, one of which uses fine metal wire such as tungsten filament and the like and the other utilizes a needle electrode structure. Typical corona discharger which uses the needle electrode structure is disclosed in US. Pat. application Serr No. 744,117, filed July 11, I968 in which the main discharges are performed between the needle electrode structure and the shielding member opposed to the electrode structure and the photosensitive layer of the sheet is charged by a peripheral electric field produced around the main discharges. This invention is directed to an improvement of such corona discharger.

In such arrangement as the main discharges are carried out from each of the needles provided on the electrode structure to the shielding member or wire faced to the needles, the generation of an electric field around the main discharges is essentially limited to the neighborhood of the needle ends, and therefore the charging regions are necessarily narrowed. In order to solve this problem, it is necessary to increase the number of the needles of the electrode structure, apply higher voltage to the electrode structure or take another expedients. Such kinds of dischargers are complicated in structure or require high degree of insulation between the components used therein.

Accordingly, it is an object of the invention to provide an improved corona discharger for electrophotography with high efficiencies.

It is another object of the invention to widen the charging regions established between the electrode structure and the shielding member and increase charging efficiencies of the corona discharger.

The corona discharger of high charging efficiencies in accordance with the invention is efiectively applied not only to single corona discharging system but also to double coronadischarging system, and in latter case another advantages are superimposed as described hereinafter.

It is thus another object of the invention to efiiciently impress an uniform charge on the photosensitive sheet by providing stable positive and negative corona discharges.

Such dischargers have high discharging efficiencies and require a small high-voltage source. With such arrangement, high quality of images can be obtained without the charging irregularities. In the preferred embodiment of the invention, it is desirable to apply such corona discharger to electrostatic image forming process.

Thus, it is another object of the invention to apply a corona discharger to electrostatic image forming process thereby to impress the chargeon the photosensitive sheet and to simultaneously perform a uniform exposure.

In case that the present invention is applied to a single corona-discharging system, there arises difficult problem that the photosensitive sheet cannot be easily separated from the electrode plate disposed to accept the advancing sheet. Thus, in an automatic continuous operation system, it is difficult to smoothly feed the photosensitive sheet automatically.

It is thus further object of the invention to prevent a photosensitive sheet from electrostatically adhering to the electrode member to improve the feeding of the photosensitive sheet.

It is an aspect of the invention to widen the corona discharging patterns radially without concentrating on restricted points to extend the ionized regions, i.e., charging regions several times in area.

It is another aspect of the invention to set up increased intensity of electric field to obtain high level of concentration of ions and to obtain a uniform electrostatic charge even if high voltage is applied between the needle electrode structure and the shielding member.

It is another aspect of the invention to apply lower voltage to a positive electrode than that applied to a negative electrode or increase a spacing between the adjacent needles of a negative electrode structure more than that of a positive electrode structure.

It is another aspect of the invention to cause the photosensitive surface to be charged uniform and simultaneously cause it to be exposed to a light in full width of the discharger to provide image of good quality without charging irregularities.

It is further another aspect of the invention to feed the photosensitive sheet smoothly without substantial mechanical resistance.

The invention will be better understood from the following description taken in conjunction with the accompanying drawings, in which;

FIG. I shows a schematic diagram of the prior art discharger consisting of a needle electrode structure and two shield plates,

FIG. 2 shows a schematic diagram of the discharger arranged in accordance with the present invention,

FIG. 3 is a representation of the ionized state in the neighborhood of the positive electrode in corona discharger,

FIG. 4 is a representation of the ionized state in the neighborhood of the negative electrode in corona discharger,

FIG. 5 shows a plane view of a positive, sawtooth electrode structure for corona discharge in accordance with the invention,

FIG. 6 shows a plane view of a negative, sawtooth electrode structure for corona discharge in accordance with the invention,

FIG. 7 shows a schematic diagram of a double corona discharger to which the present invention is applied,

FIG 8 shows a diagram of arrangement of one embodiment in which two shielding members are faced to a center electrode in accordance with the present invention.

FIG. 9 shows cross-sectional view of the corona discharger having the electrode arrangement shown in FIG. 8 in accordance with the invention,

FIG. 10 shows a diagram of arrangement of another embodiment in which a transparent electrode plate is provided with a plurality of needle electrodes in accordance with the invention,

FIG. 11 shows cross-sectional view of the corona discharger having the electrode arrangement shown in FIG. 8 in accordance with the invention,

FIGS. 12 and I3 show modified embodiments of the elec trode structures in which a plurality of electrodes are disposed on a transparent plate members,

FIG. 14 shows cross-sectional view of the corona discharger and its associated elements in which a rotatable electrode is used in accordance with the invention,

FIG. 15 shows cross-sectional view of another form of corona discharger and its associated elements in which two needle electrode structures are opposed to each other, and

FIG. 16 shows cross-sectional view of further another form of discharger and its associated elements in which three discharging wires are utilized.

Referring now to FIG, 1, there is shown an arrangement of the prior art needle electrode structure and a pair of shielding plate members for use in a corona discharger. The needle electrode structure I is provided with a plurality of needles in the alternative form on the opposite sides. A pair of shielding plate members 3 are disposed on the opposite sides of the electrode structure opposite to the needles 2 thereof. A power supply 4 is connected at the negative terminal to the needle electrode structure 1 and at the positive terminal to the shielding plate members 3 to apply voltage between the electrode structure I and both of the shielding plate members 3. In the illustrated example, both shielding members 3 are grounded, as shown in FIG. I, and the positive terminal of the power supply is also grounded. In such kind of the prior art arrangement, upon the application of voltage between the electrode structure and the shielding members, corona discharge F is initiated from the end of each needle of the electrode structure to the shielding members 3 and is continued therebetween. Such corona discharge is concentrated on each of restricted points of the shielding members. Accordingly, it is evident that ionized regions, and thus charging areas are limited. FIG. 2 shows an arrangement of a pair of shielding members faced to a needle electrode structure for use in the corona discharger in accordance with the present invention. The corresponding elements shown in FIG. 2 have the same reference numerals correspondingly to those of FIG. 1. The needle electrode structure I may take any forms such as form wherein a plurality of projections are integrally formed on the opposite sides, sawtooth electrode structure or the like, and such forms of structures fall within the category of the needle electrode structure described herein. Preferably, the electrode structure 1 has alternative projections, called needles," on the opposite sides thereof.

As being apparent from FIG. 2, each of the shielding members 3 is formed in the corrugated form in such a manner that each of concave portions forms an arc centering around the end of each needle of the electrode structure. Thus, the cycle of the corrugations of shielding members corresponds to the spacing between the adjacent needles or projections.

According to one embodiment of the present invention, each needle is distant from the adjacent needle by mm., the bottom of the concave portion of the shielding members is spaced from the end of the respective needles by 10 mm., the distance between the end of each needle and the photosensitive surface of the medium (not shown) is 10 mm. Negative voltage of 7 kv. is applied from a power supply 4 to the needle electrode structure 1, and the shielding members 3 are grounded or connected to positive terminal of the power supply. Upon the application of voltage between the needle electrode structure 1 and the shielding members 3, each corona discharge does not concentrate on a point location on the shielding members. Instead, each corona discharge radially spreads, and therefore ionized regions and thus charging areas are widen. In the illustrated embodiment, the charging regions are extended about several times as compared with the prior art discharger as shown in FIG. 1.

The corona discharger shown in FIG. 2 is applicable not only to a single corona discharging scheme but also to a double corona-discharging scheme effectively.

Before discussing the illustrated embodiments, the double corona discharge will be discussed hereinafter: This double corona discharge means that the positive and negative corona discharges are simultaneously carried out in a corona discharger. With the use of the needle electrode structures for electrodes of the corona discharger, development of the negative corona discharge is relatively difiicult as compared with that of the positive corona discharge. This phenomenon is, in general, called as polarity efiect. Continuing the discussion, in the case of the positive corona discharge, electrons between electrodes are attracted by the positive electrode and then collide with neutral particles on the way, thereby ionizing the neutral particles. Then, light electrons quickly reach the positive electrode to discharge, while heavier positive ions remain unmoved substantially. The positive ions are distributed in a dendriform as space charges, as shown in FIG. 3. These space charges assume the extension of the positive electrode.

On the other hand, in the case of negative discharge, secondary electrons produced by bombardment of electrons against neutral particles are forced not to enable the ionization due to the effect of electric field of the negative electrode, and the secondary electrons repel to the negative electrode. Thus, the distribution of the secondary electrons becomes radial, with the result that negative corona discharge cannot be readily established. Under such conditions, when voltaGE of the same value is applied to the positive and negative electrodes in the double corona discharger with the needle electrode structure, positive corona discharge is unstable in discharge condition and are inclined to transit to spark discharge due to the polarity effect described hereinbefore. While, negative corona discharge is not easily established, and therefore it is impossible to impress a suitable charge on a photosensitive sheet.

In accordance with one embodiment of the present invention, the corona discharger which uses the needle electrode structures is operated by applying lower voltage to the positive electrode structure than that applied to the negative electrode structure.

According to another embodiment of the invention, as shown in FIG. 5, the positive electrode structure 1 is made of stainless steel or other conductive material of about l/ 10 mm. in thickness, and a plurality of sawtooth electrodes 2 are formed in the alternative form on the opposite sides thereof. The end of each electrode is formed in the wedge form. While. the negative electrode structure I for use with the positive electrode structure shown in FIG. 5 is in the form as illustrated in FIG. 6. The negative electrode structure is structurally similar to the positive electrode structure shown in FIG. 5 with the exception that the spacing P between the peaks of the adjacent sawtooth electrodes 2 of the negative structure is more wide than spacing P between the peaks of the adjacent sawtooth electrodes of the positive structure shown in FIG. 5. The needle ends of each of the positive and negative electrode structures so produced are opposed to the respective shielding members on the opposite sides. And, the positive and negative electrode structures are arranged on the opposite sides of the photosensitive sheet.

If desired, the needle ends of each of the electrode struc tures may be bent at the desired angle. I

Further, according to another embodiment of the invention, two embodiments just mentioned above are preferably combined. In other words, the voltages of different value are applied to different forms of the electrode structures.

More specifically, lower voltage is applied to the positive electrode structure having narrow electrode spacing, while higher voltage is applied to the negative electrode structure having wide electrode spacing. In such double coronadischarging schemes, the development of corona discharge is suppressed and stabilized not to transit to the spark discharge at the side of positive electrode structure. On the other hand, the development of corona discharge is facilitated at the side of the negative electrode structure. Therefore, the double corona discharger in accordance with the invention maintains stable and continuous corona discharging conditions during operation and is capable of impressing satisfactory charge on the photosensitive sheet without charging irregularities. In addition, according to the present invention, charging efficiencies are considerably improved.

FIG. 7 shows a schematic diagram of the double corona discharger in accordance with the present invention. In the figure, one negative electrode structure 1' is arranged at one side of a photosensitive sheet P, while a positive electrode structure I is disposed opposite to the negative electrode structure at the opposite side of the photosensitive sheet P. A pair of shielding members 3' and 3 are faced to each other on the both sides of the negative electrode structure 1'. Similarly, a pair of shielding members 3 and 3 are opposed to each other on the opposite sides of the positive electrode structure I. These shielding members are preferably corrugated, for example, in such manner as described hereinbefore in connection with FIG. 2. The negative electrode structure I is connected to the negative terminal of a power supply 4, and the faced shielding members 3 and 3 are connected to the positive terminal of the power supply. On the other hand, the positive electrode structure I is connected to the positive terminals of the same power supply 4, and the faced shielding members 3 and 3 are connected to the negative terminal of the power supply 4. In accordance with one embodiment of the present invention, the negative and positive electrode structures 1' and l are different in width, and therefore both sides of the negative and positive electrode structures are not aligned with each other.

In the conventional double corona discharger, one electrode structure is arranged to align with the other electrode structure, and corona discharges established on the opposite sides of the photosensitive sheet located between the respective electrode structures are necessarily in align with one another at the ends of the negative and positive electrode structures. In such kind of corona discharge, since high voltage is required (for example kv.) to establish the charging regions sufficient to apply a satisfactory charge to the sheet, high electric field is set up between the negative and positive electrode structures 1' and 1. As a result, such positive ion streams as plasma are produced which are inherent in negative corona discharge, and noncharging regions are partially caused. In addition, there is a possibility that the positive ion streams grow and transit the corona discharge to the spark discharge.

With the arrangement constructed in accordance with the invention, as shown in FIG. 7, since the negative and positive electrode structures are not aligned with each other at the ends thereof and displaced at the predetermined distance X, the peripheral electric fields f and f are displaced from each other correspondingly to the displacement of the electrode structures, with the result that ionized or charged regions are extended. Further, since the distance between the electrode structures is sufiiciently long, high voltage may be applied to produce high strength of electric fields. Thus, ionized regions are extended and the concentration of ions is increased. Accordingly, uniform charge to the photosensitive surface of the sheet can be attained over the extended charged regions.

In a typical embodiment, the same structure as aforementioned embodiment was taken in the spacing between the adjacent needle electrodes, distance between the needle end of the electrode structure and the shielding member, and distance between the needle end thereof and the photosensitive surface. The displacement X from the side of one electrode structure to the side of the other structure was 4 mm., the applied voltage was 4.2 kv., at the negative electrode structure as well as the positive one, and the photosensitive sheet was fed at the rate of 4 cm. per second. With such arrangement as mentioned above, the photosensitive surface of the sheet was given a uniform and satisfactory charge.

The photosensitive sheet applicable to the present invention may take any forms. Especially, it is preferable to apply the corona discharger in accordance with the present invention to the photosensitive paper disclosed in the Us Pat. application Ser. Nos. 563,899 and 571,538, filed July 8, 1966 and filed Aug. 10, I966 respectively in which an electrophotographic technique has been proposed which uses the sandwich like photosensitive paper having a photoconductive Iayer' interposed between a conductive base and an insulating layer and, after applying a primary charge to the photosensitive paper, an electrostatic image pattern is formed on the insulating layer of the photosensitive paper by irradiating intended pattern thereon and simultaneously performing alternating current corona discharge between the electrodes. Alternatively, in this case, the electrostatic image pattern can be fonned by direct current secondary discharge of the polarity reverse to the primary discharge, instead of the alternating corona discharge mentioned above. It should be noted that the photosensitive sheet which has a photoconductive layer interposed between both outside insulating layers may be conveniently applied to the invention.

In general, the corona discharger has a discharging electrode disposed at the center of the housing and the discharge is performed between this discharging electrode and the shielding members arranged opposite to the electrode. On the other hand, a simultaneous exposing discharger is arranged to irradiate the intended pattern onto the photosensitive layer through the housing thereof. Thus, in case the discharger with the needle electrode structure is applied to the simultaneous exposing system, the exposure irregularities would be caused and the quality of image pattern produced on the photosensitive medium would be injured considerably, because the exposure is disturbed by the discharging electrode located within the light path for exposure.

In accordance with another embodiment of the invention, the corona discharger with the needle electrode structure is effectively applied to such kind of process as the electrostatic image formation mentioned above to solve the problem. FIG. 8 shows an arrangement of the electrodes. As shown in FIG. 8, between two needle electrode structures 17, and 17 faced to each other, an counter electrode 16 made of conductive wires or fine plate is disposed at the center position at equal intervals.

FIG. 9 shows a corona discharger which utilizes the electrodes arranged as shown in FIG. 8. The needle electrode structures l7 and 17 are connected to the negative terminal of a power supply 18, and the counter electrode 16 is the grounded positive terminal of the power supply. When high voltage is applied between the needle electrode structures and the counter electrode, a corona discharges occur between one electrode structure l7 and the counter electrode 16 and between the other electrode structure 17 and the counter electrode 16. In this manner, the photosensitive surface of a photosensitive sheet 15 is charged and simultaneously the exposure can be attained through the light path formed between the needle electrode structures 17, and 17 In this case, the counter electrode 16 is very fine to the extent that it is negligible (for example, 1 mm. 4?), and therefore the charging width 1 is substantially equal to the exposure width. Thus, in accordance with the corona discharger with needle electrode structures of the invention, the exposing and charging steps are simultaneously and effectively performed without exposure irregularities.

In the illustrated embodiment, the needle electrode structure was made of stainless steel or other conductive material of the order of0,l mm, in thickness and a plurality of sawteeth were formed at the one side. Preferably, the positive electrode structure has sawteeth at intervals 4 mm., and the negative electrode structure has sawteeth at intervals of 8 mm. A pair of the needle electrode structures were prepared in the manner as mentioned above and were arranged so that the sawteeth of one electrode structure are faced to those of the other electrode structure in the alternative form with a space I, being 8 mm. and a space 1 being 10 mm. Voltage of 8 kv. was applied between the needle electrode structures and the counter electrode to effectively operate the corona discharger in accordance with the invention. For the purpose of obtaining the same effect, sawtooth electrode structure may be replaced by such electrode structure that an elongated conductor is provided with a plurality of needles planted thereon at the predetermined spaces.

FIGS. 10 and 11 show another embodiment of an arrangement of the electrodes and a corona discharger utilizing the same. A transparent electrode plate 19 made of NESA glass or the like is provided with a plurality of needlelike electrodes deposited to the opposite end sides by transparent conductive adhesives. Alternatively, transparent needle electrodes may be formed on the transparent plate by vaporization. Then, a pair of shielding members 12 are arranged opposite to the needle electrodes 10 of the electrode structure. As shown in FIG. 11, the negative terminal of a power supply 18 is connected to the transparent conductive coating 11 on the plate 19, and the grounded positive terminal of the power supply is connected to the shielding member 12. When voltage is applied between the electrode structure 19 and the shielding members 12, corona discharge is initialized therebetween. Exposure is simultaneously performed through the transparent electrode structure 19 to light beam radiated from a light source 14. In this embodiment, the exposure width is equal to the discharging width 21, plus the electrode width 1 and the exposure width may be freely determined on the basis of the electrode width 1 The electrode structure as shown in FIG. 10 may be formed by depositing metal vaporized film 11 on a glass plate 19 in such as manner that sawteeth are formed on the opposite end sides of the vaporized film, as being shown in FIG. 11. Alternatively, the needle electrode structure in accordance with the invention may be formed by fixing conductive material such as tungsten wire or stainless wire on the metal deposited film by conductive adhesives, as shown in FIG. 13.

In accordance with the corona discharger. uniform and satisfactory charge can be impressed on the photosensitive sheet moving at the speed of -7 cm. per second, and simultaneously the exposure can be effectively carried out through the full width of the electrode structure without irregularities. Accordingly, the image pattern of good quality can be obtained, and simultaneous exposing and charging process can be improved.

In accordance with another embodiment of the invention, the corona discharger is characterizedby a rotatable roller electrode as a counter electrode provided on the side of advancing photosensitive sheet. In the prior art device, since the photosensitive paper is charged by the corona discharger during operation, the photosensitive paper electrostatically adheres to a stationary electrode plate, and therefore in many cases it is difficult to smoothly feed the photosensitive paper.

The problem can be solved by the provision of a rotatable roller electrode faced to the discharging electrode. FIG. 14 shows a corona discharger and its associated elements constructed in accordance with the invention. A housing 21 for the discharger includes a needle electrode structure 22 and a shielding plate member 23 faced thereto. A rotatable roller electrodes 24 is provided adjacent to the discharging opening of the housing 21 for receiving an advancing photosensitive paper P guided by a guiding plate 30. The roller electrode 24 may be freely rotatable or may be drived by driving mechanism (not shown).

FIG. shows another embodiment of the corona discharger in accordance with the invention. The discharger has a shielding plate 23 and needle electrode structures 22 and 22' faced thereto accommodated within a housing 21. A rotatable electrode 24 is positioned oppositely to the shielding plate member 23. The needle electrode structures 22 and 22 are connected to a negative potential source, and the shielding plate member 23 and the rotatable roller electrode 24 are connected to the ground at positive potential.

FIG. 16 shows another embodiment of the present invention in which a housing has three fine metal wires 25 and a shield ing member 23 accommodated therein and a rotatable electrode 24 is provided in front of the opening of the housing.

In accordance with the embodiment of the invention in which the rotatable electrode is used for feeding mechanism of the photosensitive paper, the problem of adhesion of the paper to the electrode can be effectively solved. In practice, when the roller electrode of l6 mm. in diameter was used, the photosensitive paper was advanced at the rate of 50 mm. per second and negative voltage of 7 kv. was applied to the electrode structure, this system exhibited successful result. In other words, with the prior art device, the photosensitive paper has encountered considerable resistance to feed it, while with the use of the discharger provided with the rotatable electrode, the photosensitive paper could be smoothly advanced without appreciable resistance.

It should be noted that one or more of the embodiments described herein can be advantageously combined with another embodiment.

What is claimed is:

l. Apparatus for imparting charge to the surface of a chargeable member adapted for use in electrophotography comprising a conductive element juxtaposed with said chargeable member surface, and a first electrode providing corona discharge directed onto both said conductive element and said chargeable member surface and comprising an elongated body tapering to a corona discharge point, said conductive element having a concave surface juxtaposed with said first electrode discharge point.

2. The apparatus claimed in claim 1 including in addition a support member supporting said first electrode and a second electrode, said second electrode comprising an elongated body tapering a corona discharge point, said conductive element having first and second concave surfaces respectively juxtaposed with said first and second electrode discharge points.

3. The apparatus claimed in claim 2 wherein said conductive element comprises an elongated sheet having corrugations defining said first and second concave surfaces.

4. The apparatus claimed in claim 1 including in addition a support member supporting said first electrode and a second electrode, said second electrode comprising an elongated body tapering to a corona discharge point, said support member intervening said first and second electrodes, and including a second conductive element juxtaposed with said chargeable member surface, said second conductive element having a concave surface juxtaposed with said second electrode discharge point.

5. The apparatus claimed in claim 4 wherein said first and second electrodes are spaced along said support member.

6. The apparatus claimed in claim 1 including a second electrode juxtaposed with said first electrode and said conductive element and adapted to support said chargeable member.

7. The apparatus claimed in claim 6 wherein said second electrode comprises a conductive roller.

8. The apparatus claimed in claim 4 wherein said support member includes a translucent expanse adapted to expose said chargeable member to radiant energy therethrough.

9. The apparatus claimed in claim 8 wherein said support member is comprised of translucent conductive material.

10. Apparatus for imparting charge to opposed surfaces of a chargeable member adapted for use in electrophotography comprising:

a. a first conductive element juxtaposed with a surface of said chargeable member,

b. a plurality of first electrodes each providing corona discharge directed onto both said first conductive element and said chargeable member surface,

c. a second conductive element juxtaposed with the opposite surface of said chargeable member, and

d. a plurality of second electrodes each providing corona discharge directed onto both said second conductive element and said chargeable member opposite surface,

said first and second electrodes each comprising an elongated body tapering to a corona discharge point, discharge points of adjacent one of said first electrodes being more closely spaced to each other than are the discharge points of adjacent ones of said second electrodes.

11. The apparatus claimed in claim 10 further including means applying positive voltage to said first electrodes and negative voltage to said second electrodes, said negative voltage being of greater magnitude than said positive voltage.

12. Apparatus for imparting charge to opposed surfaces of an elongated chargeable member adapted for use in electrophotography and having a lateral expanse, comprising a first conductive element juxtaposed with a surface of said chargeable member, a first electrode providing corona discharge directed into both said first conductive element and said chargeable member surface, a second conductive element juxtaposed with the opposite surface of said chargeable member, and a second electrode providing corona discharge onto both said second conductive element and said chargeable member opposite surface, said first electrode and said second electrode each comprising an elongated body tapering to a corona discharge point, said first electrode corona discharge point being laterally displaced from said second electrode corona discharge point.

13. The apparatus claimed in claim 12 further including means supplying voltages of respectively opposite polarities to said first electrode and said second electrode.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent 3,624, 392 Dated November 30, 1971 Akira Kurahashi et al. Inventor(s) It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Cancel everything and substitute the reprinted soft copy.

Signed and sealed this 8th day of May 1973.

(SEAL) Attest:

EDWARD M FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents RM PC3-1350 10-69) USCOMM-DC 80376-969 v u 5 GOVERNMENT rnlmmc OFFICE t 19 01ss:34 

1. Apparatus for imparting charge to the surface of a chargeable member adapted for use in electrophotography comprising a conductive element juxtaposed with said chargeable member surface, and a first electrode providing corona discharge directed onto both said conductive element and said chargeable member surface and comprising an elongated body tapering to a corona discharge point, said conductive element having a concave surface juxtaposed with said first electrode discharge point.
 2. The apparatus claimed in claim 1 including in addition a support member supporting said first electrode and a second electrode, said second electrode comprising an elongated body tapering a corona discharge point, said conductive element having first and second concave surfaces respectively juxtaposed with said first and second electrode discharge points.
 3. The apparatus claimed in claim 2 wherein said conductive element comprises an elongated sheet having corrugations defining said first and second concave surfaces.
 4. The apparatus claimed in claim 1 including in addition a support member supporting said first electrode and a second electrode, said second electrode comprising an elongated body tapering to a corona discharge point, said support member intervening said first and second electrodes, and including a second conductive element juxtaposed with said chargeable member surface, said second conductive element having a concave surface juxtaposed with said second electrode discharge point.
 5. The apparatus claimed in claim 4 wherein said first and second electrodes are spaced along said support member.
 6. The apparatus claimed in claim 1 including a second electrode juxtaposed with said first electrode and said conductive element and adapted to support said chargeable member.
 7. The apparatus claimed in claim 6 wherein said second electrode comprises a conductive roller.
 8. The apparatus claimed in claim 4 wherein said support member includes a translucent expanse adapted to expose said chargeable member to radiant energy therethrough.
 9. The apparatus claimed in claim 8 wherein said support member is comprised of translucent conductive material.
 10. Apparatus for imparting charge to opposed surfaces of a chargeable member adapted for use in electrophotography comprising: a. a first conductive element juxtaposed with a surface of said chargeable member, b. a plurality of first electrodes each providing corona discharge directed onto both said first conductive element and said chargeable member surface, c. a second conductive element juxtaposed with the opposite surface of said chargeable member, and d. a plurality of second electrodes each providing corona discharge directed onto both said second conductive element and said chargeable member opposite surface, said first and second electrodes each comprising an elongated body tapering to a corona discharge point, discharge points of adjacent one of said first electrodes being more closely spaced to each other than are the discharge points of adjacent ones of said second electrodes.
 11. The apparatus claimed in claim 10 further including means applying positive voltage to said first electrodes and negative voltage to said second electrodes, said negative voltage being of greater magnitude than said positive voltage.
 12. Apparatus for imparting charge to opposed surfaces of an elongated chargeable member adapted for use in electrophotography and having a lateral expanse, comprising a first conductive element juxtaposed with a surface of said chargeable member, a first electrode providing corona discharge directed into both said first conductive element and said chargeable member surface, a second conductive element juxtaposed with the opposite surface of said chargeable member, and a second electrode providing corona discharge onto both said second conductive element and said chargeable member opposite surface, said first electrode and said second electrode each comprising an elongated body tapering to a corona discharge point, said first electrode corona discharge point being laterally displaced from said second electrode corona discharge point.
 13. The apparatus claimed in claim 12 further including means supplying voltages of respectively opposite polarities to said first electrode and said second electrode. 